1. Field of the Invention
The present invention relates to a thin film transistor and a flat panel display device including the same, and more particularly, to a thin film transistor of which a semiconductor layer can be easily patterned uniformly and a flat panel display device including the same.
2. Description of the Related Technology
A thin film transistor used in a flat panel display device such as a liquid crystal display device, an organic electroluminescent display device or an inorganic electroluminescent display device is used as a switching element for controlling the operation of a pixel and a driving element for driving the pixel.
The thin film transistor includes a source electrode and a drain electrode, a semiconductor layer including a channel region formed between the source electrode and the drain electrode, and a gate electrode which is insulated from the source electrode, the drain electrode and the semiconductor layer.
When thin film transistors having the above-mentioned structure are embodied in an array, each of the thin film transistors operates as an independent switching element. Accordingly, the semiconductor layer may be patterned so as to prevent crosstalk between adjacent thin film transistors. In a conventional silicon thin film transistor, a silicon semiconductor layer is patterned using photolithography.
Recently, as research into flexible display devices has increased, a plastic substrate has been used instead of a conventional glass substrate. However, the plastic substrate cannot be subjected to a high-temperature process.
Accordingly, a method of forming a thin film transistor on a plastic substrate at a low temperature has been suggested. Particularly, research has gone into organic thin film transistors which can be manufactured at a low temperature, that is, thin film transistors in which the semiconductor layer is formed of organic material. However, in an organic thin film transistor, the organic semiconductor layer cannot be patterned using a conventional photolithography. That is, if a wet or dry etching process accompanying the conventional patterning process is used, the organic semiconductor layer can be significantly damaged and thus the etching process cannot be used.